6136 / 6186 "premium" tubes

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Any thoughts on using 6136 vs 6AU6 or 6186 vs 6AG5 tubes ? From the RCA datasheet:

"Featured in the design of the 6136 is a structure utilizing tube parts which are precisely made and accurately fitted to minimize variations in electrical characteristics due to mechanical movement and to minimize microphonic effects. In addition, the design incorporates a pure-tungsten heater having high mechanical strength to give long life under conditions of frequent "on-off" switching...The 6136 is manufactured under rigid control and undergoes rigorous tests to ensure its "premium" quality as follows...."

Sounds pretty good to me
I've found a few so far in my stash. Time to look for more...